The present disclosure relates to a semiconductor device, and more particularly to a power semiconductor device.
In recent years, with the spread of information technology, higher-speed and lower-power implementation for electronic apparatuses, such as computers, information storage devices, mobile phones, and portable cameras, has been in high demand. Among the components of these electronic apparatuses, key semiconductor electronic components such as power supplies, motor drivers, and audio amplifiers greatly affect the performance of the electronic apparatuses, and power semiconductor devices incorporating power devices greatly affect the performance of these semiconductor electronic components. Therefore, demands for higher speed and lower power for power semiconductor devices are especially high.
A power transistor constituting a power semiconductor device generally has a configuration of transistors called cells connected in parallel. In this configuration, the sources alone, and the drains alone, of the cells are individually connected to one another via interlayer interconnects called buses. The buses are connected to contact pads, which are then connected to external connection terminals such as leads via wires.
In supply of a current to the transistors from outside the semiconductor device, it is ideal that the current flows in a bus uniformly to permit uniform current supply to the cells. However, the bus has a slight resistance, and the influence of this resistance increases as the speed of the power semiconductor device becomes higher, resulting in that, while the current flows easily in some part of the bus, it does not flow easily in the other part thereof. This is likely to cause phenomena such as that the bus is damaged due to electromigration caused by current concentration and that the current concentrates in some cells causing damage, and this degrades the reliability.
To prevent occurrence of the above phenomena, it has been examined to connect a plurality of pads to a bus or divide a bus into a plurality of regions (see Japanese Patent Publication No. 2002-164437 and Japanese Patent Publication No. 2008-140970, for example).